Mother's milk is recommended for all infants. However, in some cases breast feeding is inadequate or unsuccessful or inadvisable for medical reasons or the mother chooses not to breast feed. Infant formulas have been developed for these situations.
Generally infant formulas are available in powder form, concentrated liquid form, or ready to feed liquid form. Powdered infant formulas are the most popular form; primarily due to their cost and nutritional quality. The key disadvantage with powdered infant formulas is the inconvenience of preparation. The powdered formula must be spooned into a sterilised drinking vessel such as a baby bottle, water which has been boiled and allowed to cool is poured into the drinking vessel to reconstitute the formula and the drinking vessel is then sealed and shaken to ensure the powder has been dissolved. It may be noted that milk-based nutritional compositions such as infant formula provide excellent substrates for bacterial growth. Therefore, to avoid any bacterial growth, the formula should be consumed immediately after reconstitution.
If prepared and consumed in this manner, powdered infant formulas provide a safe and nutritionally good substitute for mother's milk in the situations described above. However, the process needs to be repeated every time a feed is required. It may readily be seen that this may not always be convenient and, as a consequence, many parents and other caregivers do not prepare the formulas properly and hence expose the infant to the risk of infection. For example, the water may not be boiled prior to use in which case any pathogens in the water are fed to the infant. Usually water sources in developed countries are reasonably safe but this may not be the case everywhere. Alternatively, batches of the infant formula may be prepared and then stored until needed. Unfortunately, if any pathogen has contaminated the formula, it then has time to replicate.
Infant formulas in concentrated liquid form suffer substantially the same disadvantages as powdered infant formulas. Hence they do not provide a better solution. Infant formulas in ready to feed form should in theory provide a solution to the inconvenience of preparation. However, they have their own disadvantages; in particular they are much more costly and bulky. Further, it is often necessary to provide them in a size enabling multiple feeds. However once opened for the first feed, a contamination risk remains.
Similar issues arise with other nutritional compositions for children such as growing up milks and infant cereals, and for nutritional compositions for adults such as feeds used in health care environments.
In view of these concerns and with the intention of providing liquid nutritional compositions such as infant formula in a convenient and safe manner, various devices for the preparation of individual servings of such compositions have already been proposed. For example WO 2004/107940 proposes a device having a first water chamber in which water to be used in the reconstitution of the composition is boiled then transferred to a second chamber in which it is held until required at which point it is reheated to the desired temperature of administration and dispensed into a baby bottle where it is mixed with powdered infant formula to prepare a single feed in the conventional way. Alternatively, the powdered infant formula and reheated water may be mixed together before being dispensed into the bottle. WO 03/084377 proposes a device comprising a sterilisation unit, a container and dispenser for the powdered infant formula, a water reservoir and a water pump all linked to a controller such as a microprocessor. This device would sterilise baby bottles, dispense the desired amount of infant formula into the sterilised bottle, pre-boil the water and then maintain it at a suitable temperature, and finally dispense the desired amount of water at the desired temperature into the bottle to reconstitute the infant formula.
These known devices are mainly directed towards providing single servings of infant formula in a convenient manner. However, the immune defences of infants and young children are generally not fully developed and, as a result, these populations are particularly vulnerable to both bacterial and viral infections. For example, they may be prone to infections in circumstances where the immune system of a healthy adult would resist infection or they may suffer more serious consequences as a result of infection than would a healthy adult.
Similar difficulties may arise in populations where the immune system is compromised such as the elderly. The consequence of this is that dispensing devices that produce products which are perfectly safe for healthy adults may not be able to produce products which meet the increased safety standards required for products to be consumed by subjects having immature or compromised immune systems. Dispensing equipment may provide a more convenient way to prepare single servings of nutritional compositions such as infant formula but its use brings new problems that are not encountered using traditional methods. This is not simply a question of sterilising the water which will be used to reconstitute the composition, attention must also be paid to such questions as the possibilities of bio-adhesion and build-up of biofilms within the equipment itself and the consequences of adhering bacteria or biofilms detaching and contaminating the previously sterilised water.
It has been observed that such biofilms may be formed within dispensing equipment even if the water dispensed therefrom has previously been boiled. It is thought that this may occur because it is very difficult to ensure that such previously boiled water remains sterile as this would entail a complete separation from the atmosphere. Once the water is again contaminated by bacteria at however low a level, it is possible that, over time, bio-adhesion will occur and biofilms will grow and adhere to surfaces with which the water is in contact, particularly in corners and crevices. Thus, although the microbial content of the water itself may be perfectly satisfactory for the preparation of infant formula, the recontamination of the water with bacteria from the atmosphere nevertheless allows biofilms to grow within the dispensing equipment parts of which films may detach and contaminate water dispensed from the equipment at a later stage.
Once a biofilm has formed, it is almost impossible to remove it completely. It may be possible to kill most of the bacteria in the film but the film itself is difficult to dislodge and can then serve as a substrate and nutrient for any live bacteria remaining or newly arriving to recolonise the surface in question.
In order that the scale of this challenge may be understood, it may be noted that the maximum microbial count recommended by Swiss legislation for products dispensed from vending machines is 100000 colony forming units (cfu) per ml whereas the maximum recommended count for infant formula is around 100 cfu/ml.
Therefore, although it is clear that use of dispensing equipment can greatly facilitate ease of preparation of nutritional compositions such as infant formulas, such use brings with it new safety concerns. There is, therefore, clearly a need to provide dispensers for such products with improved safety features.